Halloween?
by foolishmundanes
Summary: Will and Jem have never celebrated Halloween before, and Tessa attempts to introduce them to the mundane holiday.


**I thought this was a cute idea, so I did a thing. So this is a modern-day take of how I thought Will and Jem might react to Halloween. And they're still Nephilim. I really like oblivious Will and Jem. Also, POVs change constantly in this, and I hope it's not at all confusing.**

**Enjoy! :D**

**Disclaimer: **_I do not own The Infernal Devices or anything else mentioned in this story._

* * *

It was late October, and in just a few hours, it would be the 28th. A few of the inhabitants of the London Institute, Will, Jem, and Tessa, were in the library discussing a meeting they had spied on for the second time.

Somehow, though, they fell upon the topic of Halloween.

As it turns out, both Will and Jem had celebrated the holiday not once. Tessa, who lived a mundane life for sixteen years, was absolutely taken by surprise when hearing that they've never celebrated it. Of course, they had lived mundane lives too, so surely they must've done _something _on the holiday.

When she was living in New York, practically everyone participated in it. So hearing this was the probably the most normal, yet dreadful thing she's heard so far in London.

"Wait," said Tessa, the oddest look on her face, "you're telling me that you have never took part in Halloween. _Ever._ Not once. At all." She stared at the two boys in front of her, eyes wide. Jem looked over to his _parabatai_, Will, who shrugged.

"We don't really celebrate mundane holidays," Jem told her calmly, "other than Christmas, of course." He looked completely unaffected, while Tessa was gaping in total astonishment.

She didn't even think of hiding her surprise, and Will tried to stifle a laugh at the expression on her face. "You _have _to be kidding me. Right?"

"Tess," Will said, clearing his throat and crossing one leg over the other in his seat. "We just don't really see what the big deal is. What does one even do on such an event? Really, you make it seem more important than it actually is." Will had heard about it a few times, but never really cared for the event. He grew up in the country, and there was barely enough people there to live there to celebrate Christmas or Thanksgiving, let alone Halloween.

And besides, Will's father never allowed it anyway. Though he never understood why, but at the same time, never really cared.

An idea popped up in Tessa's brain. They both had to have to experience of the event, so clearly they were missing out on their childhood. So Tessa would give it to them.

Instead of explaining the purpose and what someone would do to them, she instead crossed her arms and replied with a smirk, "October thirty-first. I expect you both to be dressed up. Leave the rest to me."

Will raised his eyebrows, both him and Jem watching her as she pushed herself out of her chair and exited the library without looking back.

"She's up to no good," Will muttered. "I just know it."

"What did she mean by 'dress up'?" Jem inquired, taking a sip of the tea he had gotten long before this conversation even started.

Will pondered this for a moment, stroking his chin. _I expect you both to be dressed up_, repeated in his mind. He wasn't sure either, but judging by the smirk on her face, he wasn't quite sure if it would be a good thing. "Perhaps she means our gear?" he suggested, not really sure himself.

"Maybe," said Jem, tilting his head slightly with a dubious expression.

"I do hope, though, that none of this backfires on us," Will said, looking thoughtful.

Jem actually looked surprise by his statement. "Tessa? Hmm, I don't think so..." His tone came out unsurely.

Will leaned back in his seat, reaching for the book on the table near him, and he brought it to his lap. "I suppose it doesn't matter. It's just Halloween, after all." Jem sighed, and stood up. "Anyway, I've got some reading to do," he said, showing Jem _A Tale of Two Cities _with a grin, and he nodded, not quite knowing why Will would be so excited to read such a thing. He knew Tessa enjoyed the novel, but Will too? What was so special about it?

"You do that," Jem replied, deciding to just shrug it all off. Will reading was much preferred over the many other things he could be doing, or at least lied about doing. And he left the library with one last glance at Will.

—

**Halloween Day**

"You two disappoint me greatly," Tessa said with a frown, crossing her arms over her chest, her jaw setting.

Will threw his hands up. "You told us to dress up, and we did!"

Tessa made a face. Both Jem and Will were dressed all in black in their Shadowhunter gear with new Marks on them, knives in their belts; Jem carried his cane sword and Will carried a seraph blade.

"Er, right."

"Do we need to be wearing glamours?" asked Jem, pulling out his stele.

Tessa facepalmed herself, but then answered patiently, "No, James, no you do not." She took in a deep breath, trying not to get upset with them. Tessa reminded herself that they'd never done anything like this, so they clearly didn't know what to expect. She herself didn't dress up for the occasion, though she knew she should've to give them an example because this was just sad.

Tessa sighed. It was seven-thirty, and this was usually the time she went out, or at least preferred to. "Whatever. What you're wearing will have to do for now."

"Why aren't you wearing anything?" Will scowled, his eyes scrutinizing her up and down and making Tessa feel a bit insecure. "It's only fair."

"Like you know what's fair, William," Jem scoffed, and Will rolled his eyes in slight annoyance.

"I could've dressed up," Tessa said, and muttered, "I _should've_ dressed up to show you what a proper outfit could've looked like. When I said dress up, I meant in a costume. Jessamine has mundane money, you could've asked her to take you out."

Will scrunched his nose up in disgust. "As if we're asking _Jessamine_, of all people."

Moments later, as they approached the doors of the Institute leading outside, Will mumbled, "I don't even know why we're doing this."

"Did we agree to this?" Jem asked, though not unkindly.

Then Will paused, a hand on the door and Tessa huffed. She just wanted to give them this experience without being annoyed by Will for once. She was trying to help them but instead got repaid by this his irritating behavior. "Come to think of it, James, I don't think so."

_Fantastic_, Tessa thought with a glare at him. _Absolutely fantastic._

She had to think of a way to convince them, but instead, she widened her gray eyes and did a pouty face. "Please?" she asked in a small voice and put her hands together.

Tessa had seen people do that in television and movies, but wasn't really sure if it worked in real life.

"That's hardly fair either," said Jem with a sigh.

And apparently, it did.

"Fine. I'll go."

Will just stood there for a moment, staring at her long and hard, and he finally gave up. "I can't believe this," he murmured under his breath, and Tessa smiled, now satisfied with herself. "This stupid, infernal..." He kept going until the doors shut behind them, and they walked down the steps of the Institute and down the stony path.

They were greeted by small children running around neighborhoods in costumes such as vampires, werewolves, and ghosts and the like. Tessa thought nothing of it, but Will and Jem were both absolutely horrified.

"What the bloody hell is this?" Will demanded.

"Are these _children_?" Jem asked, looking absolutely astonished.

"Of course," Tessa answered smoothly, not really understanding their shock, walking ahead of them. The two boys exchanged a look, before jogging to catch up with her.

"Let me get this straight," Will said, bringing up a finger. "The mundanes are raising their kids to be little, demonic, _hellions_?"

Tessa stared at him for a second before laughing out loud. "You think—" She couldn't continue because she was laughing so hard.

When she finally calmed down, she smiled at the both of them and Jem sent Will a quizzical look. "That's too funny. No, they're not 'raising them', as you say, in that way. They're just costumes, Will, relax."

She chuckled a few more times before widening her eyes. "Drat," she muttered. "Do you guys want the full experience, or just the partial?"

Will narrowed his eyes. "Depends. What's the full experience?"

Tessa giggled. "Do you want candy?"

"Is it poisoned?" Jem asked seriously, not really understanding the concept of this 'Halloween' thing.

She grinned. "Obviously not. Do you want it or not?"

Jem shrugged, looking over to his _parabatai_, who was no longer paying attention to them, but instead the kids dressed like zombies. "Sure," Jem said for the both of them.

"Okie-doke. I won't be a minute," she promised, and ran back to the Institute, her new sneakers squeaking on the stony floor as she went to the distance.

Will sighed. "Why did I ever agree to this?"

"Because you're a sucker for a pretty face," Jem said knowingly, nudging him with his arm, and Will muttered something incomprehensible, before snorting.

Will ran his hand through his hair, quickly becoming bored. Maybe he could sneak off to a pub or something. _Candy_, he thought with an odd look, as if the word was from an entirely different language.

"This is ridiculous," Will told Jem, who was mainly focused on a ten year old girl dressed as a faerie, waving her plastic wand to and fro. "How are we supposed to spend the night with little—children when they're dressed as the beasts we _kill_, for God's sake."

He then flew straight into a string of curses, irritated with the whole situation Tessa brought him into and Jem was looking at him in amusement, and said, "Tessa said this would make up for our childhood."

Will glared. "And what sort of childhood is this? A _demonic_ one, no doubt," he grumbled. "I think Tessa's trying to mess with us."

Jem rolled his eyes. "William, now _you're_ being ridiculous."

"No, I sincerely believe that she's trying to get revenge on me for all those times I was 'rude' to her," he was saying, and Jem put his face in his hands, unable to believe how absurd his _parabatai _was being. "'_Hell hath no fury like a woman scorned_' after all."

Jem ignored him.

A few, peaceful seconds of silence passed, and Jem relished it, knowing that Will would soon interrupt his tranquility. Then: "By the Angel, is that a demon?" Will asked.

His _parabatai_ was becoming a little bit more irritated with him, but he turned around to see what Will was talking about, and sure enough, what looked like a Spider Demon was crawling on the porch of someone's house, and Jem shot straight up. "I think it may be," he said, raising his cane sword.

Will pulled out his seraph blade, murmuring, "_Eremiel_." It lit up immediately with white glowing light, and he raised it high in the air. As soon as he was about to charge, though, Tessa came with two orange, oddly-shaped baskets with two triangular eyes and noses; the mouth jaggedly pointing upwards into a twisted smile.

Tessa let out a yelp, and they turned around. "What are you two _doing_?" she asked, aghast.

Jem tilted his head and lowered his cane sword, eyeing the basket. "Is that supposed to be a pumpkin?"

She made a frustrated noise.

"There's a demon," Will pointed, "over there."

Tessa tossed her head back, and then looked at them, her face scrunched up in indignation. "Exactly what part of _COSTUME_ don't you understand?"

Will and Jem looked at each other. "I..."

She scowled and shoved the two pumpkin baskets in their hands, walking off. They silently followed her, and Will put his seraph blade back in his belt.

—

"Okay," Tessa sighed, "you two are going trick-or-treating. Do you know what that is?"

They shook their heads with innocent expressions. They both silently agreed not to say or do anything else without Tessa's consent, since both of them did not want to see her upset at them.

She raised her eyebrows. "How did you even survive all these years?" They said nothing, so she explained. "Basically you go door to door in a neighborhood, ringing on the doorbell, saying 'trick or treat!' And then the person who lives there gives you candy." She bit down on her lip to hide a smile.

"Sounds simple enough," said Jem.

Tessa nodded. "It really is, and it's fun. I'll be there to watch in case either of you wanna go back or something," she grinned. "And maybe, if we're lucky, we'll find a haunted house." She wiggled her fingers at them.

"Haunted house?" Will finally spoke up. He's been in haunted houses before, and never liked being in them. Then again, who did? Filled with normally angry spirits haunting the place... Absolutely dreadful.

Tessa shook her head. "No, it's not an _actual_ haunted house, just something with fake spider webs and other stuff in someone's garage." She distinctly remembered going into one when she was around nine years old, and she cried in absolute terror. Nate was tough as nails, though, and he comforted her throughout the whole thing. At the end, they gave her extra treats because of it.

They stared at her. "Oh," Jem said. "Lovely." Will grinned at him, and then they walked up to their first house. Fortunately for them, there was a bucket full of candy that said 'TAKE ONE' on the front porch, in the lap of a mummy. They looked over to Tessa as if asking for permission, and she nodded vigorously, looking proud of them both.

The moment Will reached for a piece of candy, though, the mummy reached up and seized his wrist. Will jumped back, causing all the candy to spill out of the bucket and onto the wooden floor of the porch. He began cursing very fluently, and then exclaimed, "BY THE ANGEL, WHAT WAS THAT?" Tessa was laughing very hard, clutching onto her stomach and gasping for air, and Jem was looking him, eyebrows raised.

The mummy let go of his wrist and took off his mask, revealing an ordinary human being. "Calm down, mate," he said, brown eyes wide. Will was scowling. "You're bloody barmy, you know that, right?"

"I am not," Will insisted, but then thought about it for a moment. "All right, maybe a tad bit, but not entirely."

The guy put on the mask once again, but not before giving Will a glare. "Just take the blasted piece and leave."

Will raised his hands up in mock surrender. "Fine, fine. But I'll have you know that mummies do not exist, you inaccurate little—"

"William," Jem interrupted, shaking his head. "Please don't."

Meanwhile, Tessa was laughing hard, clutching at her stomach and gasping for air. She would have a lot of fun tonight, she thought with a grin.

Will finally took one piece of candy from the floor as well as Jem, stuffing it into their basket before giving the poor guy a threatening look. Tessa tried to stifle her laughter, she really did, but this was too much.

They both walked off the porch and Tessa grinned at them both. "Nice job, guys. Though I think Will could maybe just tone it down a bit..."

He grumbled something she couldn't understand, but decided to ignore him as they went to the next house.

—

Jem rang on the doorbell, bouncing once on his heels and waiting very patiently for the door to open with Will on his side. Tessa was right behind them, in the shadows, observing silently with a broad smile on her face. _This isn't so bad_, Jem thought. In all honesty, it was actually sort of fun.

The door opened, revealing a little girl who was probably around five years old. She looked at the two boys in front of her, and grinned, revealing her crooked teeth with a gap in the middle. Her light blonde locks of hair that was up in a ponytail were falling into her face, and she pushed them back behind her ear.

"Trick or treat!" they both said.

The girl burst into a fit of giggles, and Jem faintly heard Tessa do the same. He cocked his head to the side in confusion.

"Aren't you two a little old for trick-or-treating?" she inquired in her meek English accent, covering her mouth to conceal her grin.

Will dropped the basket, and looked over at Tessa, who had thrown her head back, laughing. He knew she was up to something, but he had to admit, she looked so beautiful. But then again, she always looks beautiful, and even more so with each passing second... Little did he know Jem was thinking the same thoughts.

"No," Jem said, crouching down to be eye-level with her. "But maybe you're too young."

The girl gasped. "_No_!"

"Then are we too old?" Will asked, doing the same, now on his knees. Tessa smiled again, but this time it wasn't from laughter. She thought the sight was absolutely adorable.

She seemed confused, furrowing her eyebrows. "I don't...know."

Tessa, from behind, added, "You're never too old or too young for trick-or-treating!"

The girl stood on her tiptoes to see Tessa, and she smiled sheepishly. "You're pretty."

Tessa raised her eyebrows quizzically, as if she's never heard anyone say such a thing before. "I am?" she said, her tone skeptical.

Both Will and Jem forced themselves not to talk; they would most likely end up rambling for the rest of the night - but it wasn't like Will _could_ say anything, anyway.

The girl nodded with a "mhmm." Then she introduced herself. "I'm Catherine," she said.

"Like Lady Catherine de Bourgh," said Will immediately, unable to help himself. Tessa shot him a look, knowing that she was one of the antagonists in the book _Pride & Prejudice._

"Who?" Catherine asked. She placed a finger on her chin, suddenly looking thoughtful. "Lady Catherine. I like that." She sounded distant, like she was now in her own world.

Will smiled. "Well then, Lady Catherine, unfortunately we cannot stay for long, and..." She grinned toothily at his use of Lady Catherine.

"Oh, I should give you candy!" Catherine snapped her fingers, and ran inside the house to pull out an enormous bag with delicious sugary treats. It looked much too heavy for her, and Jem was about to offer to help her, but then: "Here, take it all! Mum and Dad won't notice, I think."

Will brightened, but Jem gave him a look, before returning to her. "You don't have to, we'll only take a little bit."

"Oh, I insist!" she said, pushing the bag towards them.

"She insists," said Will, raising his eyebrows and silently urging Jem to take the damn thing.

Catherine also was kind enough to give them a small wagon ("As long as you return it tomorrow!") to put the bag in. Jem continued protesting, saying that it was unnecessary for her to do all of this, but she replied, "No, you're my friends now. Please take it." She looked at them with wide eyes, a very light shade of blue on the verge of green. A mix of both, actually.

It almost seemed as if all girls used this trick on boys now. First Tessa, then Catherine. Terrific. Just terrific. _Manipulated by a five year old_, Will thought with a frown.

"What are your names?" Catherine then asked.

They all introduced themselves, and Jem promised immediately after that they'd return the wagon as soon as possible. She nodded, said a good-bye, and then shut the door. Jem and Will pushed themselves off the ground, and walked back to Tessa. She was smiling widely and she spun around once. "She's so cute!"

Will took the moment to look at Catherine's address. He had a _mnemosyne_ rune on him, so he just took a quick look at it and then it was implanted in his memory.

Jem grabbed the end of the wagon, and tugged at it. "So where to next?"

Tessa grinned.

—

"Is this the haunted house you were talking about?" inquired Will, loud eerie music floating in the air, vibrating through his chest and feet. Tessa nodded in confirmation, and she took the lead as they stepped in line to go through the "haunted house."

After waiting very patiently (all except for Will), it was finally their turn to enter. Tessa spoke a few words to the guys there, and they nodded. One guy snorted, eyeing them with amusement. Will narrowed his eyes, but then walked forward.

Tessa was right about the fake spider web thing. The place might as well have been covered in the stuff. People dressed up as zombies and corpses walked slowly to them, and Will couldn't help but laugh. This was too funny.

The room was tinted pale blue, yet the lighting itself was very dim. There were walls built up around them like a maze, and Tessa clung onto both boys so she wouldn't lose them.

He saw a married couple not too far off with their crying child. This wasn't even scary at all. _Mundanes_, he thought with a disappointed sigh.

Out of nowhere, a head appeared and cold hands began running down Will's back. He turned, and saw a girl dressed as bloody bride wink at him, and he mentally he rolled his eyes, but he gave her a small smirk that made her gasp with delight. This time he did roll his eyes.

Then, it went pitch black.

There was a loud, cringe-worthy scream that flooded the place, and the sound of a knife plunging into God knows what.

Will grimaced, and then suddenly, someone screamed into his ear, "BOO!" But he stood unmoving, completely unaffected.

He hummed faintly for a moment, then grabbed at the person's wrist, flipping them around until he was face to face with him. Luckily he had his night vision rune drawn on him, so was able to see the guy clearly in a mad scientist costume.

The lights flickered back on and Jem and Tessa stared at him with their eyes bulging out. Will coughed, and then let go of the mad scientist chap, and scratched the back of his neck. "He didn't know of personal space?"

Tessa sighed, and then they kept moving until they were at the exit, and they were handed a bit of chocolate, and then they left.

—

After going to a few more houses, Will, Jem, and Tessa finally returned back to the Institute. They had loads of candy stacked high upon the wagon. They didn't even bother using their baskets anymore.

"So, what do we do with all of this?" Jem asked, gesturing to the candy.

Tessa shrugged. "You eat it," she said simply.

Jem nearly tripped. "_All of it_? Like at once?"

She chuckled. "No, obviously. Save it for the next day or something—or in this case, the next month. Don't wanna get fat, you know."

Will glared at her, but then took a bite of one of the chocolates, and then he was in absolutely Heaven; he moaned in delight.

Tessa grinned. "See? I wasn't up to anything bad."

"No," Jem said, and he lowered voice, "but apparently we're too old for 'trick-or-treating.'"

She shook her head. "No. I did think that was funny, though. But once everyone turns like twelve or something everyone just kinda stops. Everyone who keeps doing it is cool, FYI."

Will nodded once, and so did his _parabatai_. Then he grinned, taking a seat on the nearest chair. "So, Tess, what do you have in store for us next?"

Then her face flushed red, and she snapped, "I'm not sure if I should do that, since you were constantly annoying everyone." She huffed.

"Me?" He put a hand to his heart in mock offense. "Annoying? I am not—"

"_Yes_," Jem and Tessa both cut him off, "you are."

Will rolled his eyes and walked off to his room, not ever going to admit that Halloween was probably the most entertaining thing since he lit Gabriel Lightwood's trousers on fire over a month ago.

Tessa, on the other hand, was feeling very proud of herself. Now they got to roam about London, even if they were dressed in their gear, and got to experience something normal for once. They all deserved it, after all they'd been through.

She just hoped Will won't be such a nuisance during Christmas.

* * *

**A/N: **_So here it is! Is it good? I'm hoping it is. I also hope you all enjoyed this, and if you did, please drop a review and favorite. Tell me if I should continue this with other holidays as well (and you might as well follow, if you _do_ all want me to continue), and if I get enough reviews saying so, I'll do it! :D Happy Halloween!_


End file.
